Effect of clozapine on immunoglobulin M plasma levels

Early neutrophil trajectory following clozapine may predict clozapine response - Results from an observational study using electronic health records

BACKGROUND

Clozapine has unique effectiveness in treatment-resistant schizophrenia and is known to cause immunological side-effects. A transient spike in neutrophils commonly occurs in the first weeks of clozapine therapy. There is contradictory evidence in the literature as to whether neutrophil changes with clozapine are linked to treatment response.

AIMS

The current study aims to further examine the neutrophil changes in response to clozapine and explore any association between neutrophil trajectory and treatment response.

METHODS

A retrospective cohort study of patients undergoing their first treatment with clozapine and continuing for at least 2 years identified 425 patients (69% male/31% female). Neutrophil counts at baseline, 3 weeks and 1 month were obtained predominantly by linkage with data from the clozapine monitoring service. Clinical Global Impression- Severity (CGI-S) was rated from case notes at the time of clozapine initiation and at 2 years. Latent class growth analysis (LCGA) was performed to define distinct trajectories of neutrophil changes during the first month of treatment. Logistic regression was then conducted to investigate for association between the trajectory of neutrophil count changes in month 1 and clinical response at 2 years as well as between baseline neutrophil count and response.

RESULTS

Of the original cohort, 397 (93%) patients had useable neutrophil data during the first 6 weeks of clozapine treatment. LCGA revealed significant differences in neutrophil trajectories with a three-class model being the most parsimonious. The classes had similar trajectory profiles but differed primarily on overall neutrophil count: with low, high-normal and high neutrophil classes, comprising 52%, 40% and 8% of the sample respectively. Membership of the high-normal group was associated with significantly increased odds of a positive response to clozapine, as compared to the low neutrophil group [Odds ratio (OR) = 2.10, p-value = 0.002; 95% confidence interval (95% CI) = 1.31-3.36]. Baseline neutrophil count was a predictor of response to clozapine at 2 years, with counts of ≥5 × 109/l significantly associated with positive response (OR = 1.60, p-value = 0.03; 95% CI = 1.03-2.49).

CONCLUSIONS

Our data are consistent with the hypothesis that patients with low-level inflammation, reflected in a high-normal neutrophil count, are more likely to respond to clozapine, raising the possibility that clozapine exerts its superior efficacy via immune mechanisms.

A case-control study of antipsychotic use and pneumonia-related mortality in the United Kingdom

BACKGROUND AND AIM

There is increasing evidence linking antipsychotic use with pneumonia, but limited evidence of an effect on pneumonia-related outcomes such as mortality. In this study, we aimed to examine the association of pneumonia-related death with specific antipsychotic exposure.

METHOD

Deaths analysed were those reported to a UK-based drug-related deaths database, the National Programme on Substance Abuse Deaths (NPSAD), between 1997 and September 2020. We conducted a case-control study with cases defined as pneumonia-related deaths and controls as cases with alternative causes of death. Cases were analysed by considering drugs detected at post-mortem (PM) and by drugs prescribed to the deceased at the time of their death with calculated odds ratios (ORs) adjusted to account for confounders.

RESULTS

There were 2467 PM cases and 40,128 controls; 1818 prescribed cases and 28,018 controls. Second generation antipsychotics (SGAs) were robustly associated with an increased risk of pneumonia-related death compared with those not prescribed or taking antipsychotics (PM detection adjusted OR [AOR] 1·34 [95% CI 1·15-1·55]; prescribed AOR 1·28 [95% CI 1·11-1·49]). First generation antipsychotics had no clear association with death from pneumonia (PM detection AOR 1·06 [95% CI 0·77-1·47]; prescribed AOR 0·91 [95% CI 0·71-1·17]). Amongst SGAs, olanzapine was associated with an increased risk of death due to pneumonia (PM detection AOR 1·49 [95% CI 1·22-1·82]; prescribed AOR 1·44 [95% CI 1·18-1·76]) as was quetiapine (PM detection AOR 1·34 [95% CI 1·07-1·66]; prescribed AOR 1·28 [95% CI 1·01-1·64]).

CONCLUSION

Olanzapine and quetiapine were found to increase the risk of pneumonia-related death in this NPSAD sample to a clinically important extent.

Incident infection during the first year of treatment - A comparison of clozapine and paliperidone palmitate long-acting injection

BACKGROUND

To examine the risk of infection in patients prescribed clozapine compared with patients prescribed paliperidone palmitate long-acting injection (PPLAI).

METHOD

A retrospective, 1-year, cohort study conducted on events occurring in eligible patients beginning treatment for the first time with clozapine or PPLAI between June 2017 and June 2019 in a UK mental health trust providing in-patient and out-patient services.

RESULTS

The study included 64 patients starting clozapine and 120 patients starting PPLAI. Incidence of infection was greater in clozapine starters than in PPLAI starters (28% vs 6%; p = 0.001; adjusted odds ratio 5.82 (95% confidence interval (CI) = 2.15-15.76, p = 0.001). Infectious episodes in clozapine patients were not related to changes in neutrophil counts. Incident infection in the clozapine group was highest in the first 3 months of treatment. The most commonly reported infection in the clozapine group was chest infection; however, the majority of infections were non-chest-related.

CONCLUSION

Patients starting clozapine showed a substantially increased likelihood of infection compared with patients starting PPLAI.

The Expanding Field of Secondary Antibody Deficiency: Causes, Diagnosis, and Management

Antibody deficiency or hypogammaglobulinemia can have primary or secondary etiologies. Primary antibody deficiency (PAD) is the result of intrinsic genetic defects, whereas secondary antibody deficiency may arise as a consequence of underlying conditions or medication use. On a global level, malnutrition, HIV, and malaria are major causes of secondary immunodeficiency. In this review we consider secondary antibody deficiency, for which common causes include hematological malignancies, such as chronic lymphocytic leukemia or multiple myeloma, and their treatment, protein-losing states, and side effects of a number of immunosuppressive agents and procedures involved in solid organ transplantation. Secondary antibody deficiency is not only much more common than PAD, but is also being increasingly recognized with the wider and more prolonged use of a growing list of agents targeting B cells. SAD may thus present to a broad range of specialties and is associated with an increased risk of infection. Early diagnosis and intervention is key to avoiding morbidity and mortality. Optimizing treatment requires careful clinical and laboratory assessment and may involve close monitoring of risk parameters, vaccination, antibiotic strategies, and in some patients, immunoglobulin replacement therapy (IgRT). This review discusses the rapidly evolving list of underlying causes of secondary antibody deficiency, specifically focusing on therapies targeting B cells, alongside recent advances in screening, biomarkers of risk for the development of secondary antibody deficiency, diagnosis, monitoring, and management.